Ephemeral creeks flowing again

Historically, before river regulation and agricultural modifications to the landscape, these ephemeral creeks would have flowed during large flow events.

Then, as the water in the creeks dried up, they would revert to becoming a series of waterholes/refuge pools, some small, some large.

However, many of these ephemeral creeks are now disconnected for extended periods of time from the rivers and permanent creeks that would have once supplied them with water.

Without environmental water, they would be dry most years except in big flood years such as last year.

The ephemeral creeks in the Edward Kolety-Wakool River system are the focus of a new ecological monitoring research project within the Edward Kolety-Wakool Flow-MER program which is funded by the Commonwealth Environmental Water Office (CEWO).

“Over the past few years CEWO and New South Wales Department of Planning and Environment have delivered environmental water into these ephemeral creeks using Murray Irrigation Limited’s infrastructure,” said program leader and Charles Sturt University Professor Robyn Watts.

“But we need to know more about them. This additional knowledge is needed to help deliver environmental water into the future, and to make decisions about further monitoring.”

Fish, frogs and birds will be surveyed in six ephemeral creeks, with monitoring undertaken in refuge pools prior to an environmental flow and again after the environmental flow.

Traditional ecological survey methods will be used as well as environmental DNA metabarcoding, that tests for the presence of the DNA of vertebrates in samples of filtered creek water.

Due to the widespread flooding, no environmental water was delivered to the creeks in spring 2022 because they received unregulated floodwater.

Despite this change to the study plan, the project will still provide important information about what animals were present in the waterholes of the ephemeral creeks before they flooded, and what animals moved into them during the floods.

“The project will increase our knowledge about these ephemeral creeks,” Prof Watts said.

“We want to find out what animals move into these temporary systems when they are connected to the permanent rivers, and what animals stay in them when they contract back to refuge pools.”

The project is a collaboration of government agencies, local landholders and community members, the Kolety Werkul River Rangers team from Yarkuwa Indigenous Knowledge Centre, and researchers.

“The environmental water is great for the bird life, and it’s great for the trees that were dying that hadn’t had a drink for some time, and it keeps the fish in the refuge pools alive,” said landholder Dennis Gleeson, whose main property Colligen Creek Station is a member of the Edward Kolety-Wakool Environmental Water Reference Group.

“We’ve got Murray Cod, some up to a metre long, in those pools.

“It keeps the creeks alive.”

Mr Gleeson owns a property at the top end of Cockrans Creek, one of the ephemeral creeks being monitored, and is a keen supporter of environmental water being delivered to the ephemeral creeks and of the research being done to better inform those deliveries.

“We don’t need a flood (to get water into ephemeral creeks), in drier years we can get environmental water into these creeks through the regulators.”

Landholder Les Gordon, from ‘Inglebrae’ at Burraboi, also has one of the ephemeral creeks being monitored - Jimaringle Creek - running through his property, and likes that monitoring is occurring on his land.

“Without monitoring and without saying what are we trying to achieve, there’s a whole lot of other variables we haven’t even begun to consider other than that water equals life,” he said.

“Monitoring helps provide answers.”